The objective of the proposed research is to extend our knowledge of the avian olfactory pathway by 1) identifying the sources of afferent fibers to the olfactory bulb and the telencephalic structures to which the bulb sends direct projections through the application of a procedure for visualizing retrograde neuronal transport; 2) clarifying the status of the anterior olfactory nucleus in the pigeon, especially in terms of its possible synaptic relation to bulbar fibers from the opposite hemisphere; 3) electrically stimulating forebrain sites that we have already identified as components of the olfactory pathway and exploring for evoked potentials and associated alterations in unit activity in the diencephalon and mesencephalon; and 4) working with avian species other than the pigeon in order to test the generality of the data collected from the pigeon. Alternative species will be selected for their known reliance on olfactory cues, e.g., the turkey vulture and some procellariiforms, or for possessing much larger or smaller olfactory bulbs than the pigeon, such as the species above with large bulbs and the crow with smaller.